1. Field of the Invention
The present invention relates to a power semiconductor device and a method of manufacturing the same.
2. Description of the Related Art
An insulated gate bipolar transistor (IGBT) is a bipolar transistor of which a gate is formed of metal oxide silicon (MOS) and a p-type collector layer is formed on a rear surface thereof.
Since a related art power metal oxide silicon field effect transistor (MOSFET) was developed, MOSFETs have been used in fields requiring devices having high-speed switching characteristics.
However, since the MOSFET has structural limitations, a bipolar transistor, a thyristor, a gate turn-off thyristor (GTO), and the like have been used in fields requiring high voltage.
Since an IGBT has characteristics such as low forward loss and rapid switching speeds, the use of IGBTs has been expanded into applications in which a bipolar transistor, a metal oxide silicon field effect transistor (MOSFET), and the like cannot be used.
Describing an operating principle of the IGBT, when the IGBT device is turned on, a higher voltage is applied to an anode than to a cathode, and when a higher voltage than a threshold voltage of the device is applied to a gate electrode, a polarity of a surface of a p-type body region disposed below the gate electrode is inverted, and thus an n-type channel is formed.
Electronic current injected into a drift region through a channel induces an injection of hole current from a high-concentration p-type collector layer disposed below the IGBT device, similar to a base current of a bipolar transistor.
A conductivity modulation increasing conductivity in the drift region from tens of times to hundreds of times in response to the high concentration injection of minority carrier is generated.
Unlike the MOSFET, a resistance component is greatly reduced in the drift region due to the conductivity modulation, such that the IGBT may be applied to fields requiring very high voltage.
Current flowing in a cathode is divided into electronic current flowing through a channel and hole current flowing through a junction between a p-type body and an n-type drift region.
Unlike the MOSFET, in terms of a structure of a substrate, the IGBT has a pnp structure between an anode and a cathode, but does not have a diode embedded therein, such that separate diodes need to be connected to each other in an anti-parallel manner.
The IGBT has main characteristics, such as maintenance of blocking voltage, reduction in conduction loss, increase in switching speed, and the like.
With the increased magnitude in voltage required for the IGBT of the related art, there is a need to increase a durability of the device.
However, the reduction in conduction loss and the maintenance of blocking voltage have a tradeoff relationship with each other and the latch-up occurs due to the structure of the device, such that the device may be easily destructive.
That is, a need exists for a development of the IGBT capable of maintaining the blocking voltage, reducing the conduction loss, preventing the occurrence of latch-up.
The Related Art Document below relates to an insulated gate bipolar transistor (IGBT).
However, the invention disclosed in the Related Art Document below does not disclose a buried hole accumulation part as well as the reduction of conduction loss and the prevention of latch-up, and therefore is different from the present invention.
Further, the invention disclosed in the Related Art Document below does not disclose a buried hole accumulation part, and therefore is different from the present invention.